When comparing MultiMarkdown Composer vs Quiver, the Slant community recommends MultiMarkdown Composer for most people. In the question“What are the best Markdown editors for OS X?”MultiMarkdown Composer is ranked 13th while Quiver is ranked 19th. The most important reason people chose MultiMarkdown Composer is:

CriticMarkup support

Pro

Optional Synchronized Scrolling

Pro

Multiple export options

Pro

Fast syntax highlighting

Pro

Highly customizable

Pro

Counts words, characters, lines

Pro

Can show invisible characters

Pro

Has more features than just a simple Markdown editor

Quiver is a notebook and note-taking app akin to Evernote which happens to also be able to edit Markdown files. As such, it has a lot of useful features such as: image support, file attachments, web content support and more.

Pro

Supports code highlighting

Has syntax highlighting for more than 120 programming languages.

Pro

Supports vi keybindings

For people used to vi keybindings, Quiver can be set up to work with them.

Pro

Notes can be linked to each-other

Quiver notes have unique links that can be copied and pasted into other notes to gain quick access between them.

Pro

Live preview

Quiver has live preview for both Markdown and LaTeX. This helps users to better understand the way they are formatting their files.